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ENGINEERING, CS 2023 HSC 22a

Previously, children's playground structures were constructed from 'treated pine' logs. The logs were treated with a copper chromium arsenate (CCA) solution which resisted fungi, insect attack and decay.

  1. Outline why new materials are being used to replace CCA treated logs in children's playground structures.   (2 marks)

  2. Justify a suitable material to use for a playground structure which will be exposed to the weather at all times.   (3 marks)

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i.     → CCA materials contain arsenic.

→ Arsenic is a carcinogen/poison and not considered suitable for use in children’s playground structures.

→ Other modern plastic materials also have superior characteristics for playground use including better resistance to insect attack and improved traction. 

ii.    → Compact Laminate is suitable material.

→ It is made of softwood and phenolic binder provides excellent stability over time and good abrasion resistance.

Other possible answers include:

→ Finished hardwood: resistant to corrosion and degradation in bright sunlight while also being very tough and wear resistant.

→ UV stabilised High Density Polyethylene: Provides bright colours, formability of complex shapes and low maintenance.

→ Stainless Steel: Provides good corrosion resistance, strength and wear resistance.

→ UV Stabilised ABS: Strong and light with excellent water resistance.

Show Worked Solution

i.     → CCA materials contain arsenic.

→ Arsenic is a carcinogen/poison and not considered suitable for use in children’s playground structures.

→ Other modern plastic materials also have superior characteristics for playground use including better resistance to insect attack and improved traction. 
 

ii.    → Compact Laminate is suitable material.

→ It is made of softwood and phenolic binder provides excellent stability over time and good abrasion resistance.
 

Other possible answers include:

→ Finished hardwood: resistant to corrosion and degradation in bright sunlight while also being very tough and wear resistant.

→ UV stabilised High Density Polyethylene: Provides bright colours, formability of complex shapes and low maintenance.

→ Stainless Steel: Provides good corrosion resistance, strength and wear resistance.

→ UV Stabilised ABS: Strong and light with excellent water resistance.

ENGINEERING, CS 2016 HSC 21ai

The reinforced concrete modules shown are designed for public seating. A typical use would be as a bus shelter.

Outline benefits of using this type of modular seating system.   (3 marks)

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→ Reusable moulds can be used to manufacture the modules off-site and then delivered to the site.

→ The completed modules can then be delivered to the site, resulting in fewer site disruptions.

→ More modules can be added as required.

Show Worked Solution

→ Reusable moulds can be used to manufacture the modules off-site and then delivered to the site.

→ The completed modules can then be delivered to the site, resulting in fewer site disruptions.

→ More modules can be added as required.


Mean mark 54%.

ENGINEERING, CS 2016 HSC 23b

This diagram shows the cross-section of a highway pavement drawn using AS 1100 drawing standards.
 

  1. Outline the properties of asphalt that make it suitable for highway pavement surfaces.   (3 marks)
  1. Why are geotextiles used in the construction of highway pavements?   (3 marks)
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i.    Successful answers should include 3 of the following:

Asphalt suitability

→ More durable than gravel and easier to lay than concrete.

→ Easily shaped and moulded to the contour of the road.

→ Can be driven on minutes after laying.

→ Can be easily repaired.

→ A smooth surface can be produced by pressing aggregate into substrate.

→ Flexibility allows for earth movement.
 

ii.   Reasons for using geotextiles:

→ Geotextiles are used to prevent the blockage of underground drainage by filtering silt from drainage below the surface.

→ They can also be used to prevent silt from undermining the road base, which can lead to road collapse.

Show Worked Solution

i.    Successful answers should include 3 of the following:

Asphalt suitability

→ More durable than gravel and easier to lay than concrete.

→ Easily shaped and moulded to the contour of the road.

→ Can be driven on minutes after laying.

→ Can be easily repaired.

→ A smooth surface can be produced by pressing aggregate into substrate.

→ Flexibility allows for earth movement.

ii.   Reasons for using geotextiles:

→ Geotextiles are used to prevent the blockage of underground drainage by filtering silt from drainage below the surface.

→ They can also be used to prevent silt from undermining the road base, which can lead to road collapse.


♦♦ Mean mark (ii) 38%.

ENGINEERING, CS 2018 HSC 24a

The diagram shows a scaffold supporting planks. The planks can be made from laminated timber, aluminium alloy or galvanised steel.
 

Outline an in-service advantage of each of these materials when used as a scaffold plank.   (3 marks)

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Answers could include one advantage from each material type below:

Laminated timber plank

→ Easily cut on-site to accommodate a non-standard opening.

→ Non-conductive.

Aluminium scaffold plank

→ Low density

→ Light weight makes aluminium planks easy to manoeuver on-site.

Galvanised steel planks

→ Can absorb energy through impact without shattering or fracturing (high impact resistance).

→ Appropriate for applications where the scaffold is likely to be exposed to falling loads eg concrete block laying, bricklaying, concreting and demolition work.

Show Worked Solution

Answers could include one advantage from each material type below:

Laminated timber plank

→ Easily cut on-site to accommodate a non-standard opening.

→ Non-conductive.

Aluminium scaffold plank

→ Low density

→ Light weight makes aluminium planks easy to manoeuver on-site.

Galvanised steel planks

→ Can absorb energy through impact without shattering or fracturing (high impact resistance).

→ Appropriate for applications where the scaffold is likely to be exposed to falling loads eg concrete block laying, bricklaying, concreting and demolition work.

ENGINEERING, CS 2019 HSC 21a

A bus shelter is shown.

The design of this bus shelter includes the use of toughened glass panels.

Outline advantages of using toughened glass for this bus shelter.   (3 marks)

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→ Flexural strength is high.

→ The risk of serious injury is reduced as toughened glass breaks into smaller pieces when broken by applied load.

→ Withstands chipping during transportation and insulation due to strong edge strength.

Show Worked Solution

→ Flexural strength is high.

→ The risk of serious injury is reduced as toughened glass breaks into smaller pieces when broken by applied load.

→ Withstands chipping during transportation and insulation due to strong edge strength.


Mean mark 55%.